New records and description of fifty-four new species of aquatic beetles in the genus Hydraena Kugelann from South America (Coleoptera: Hydraenidae) Author Perkins, Philip D. text Zootaxa 2011 2011-10-28 3074 1 198 journal article 31530 10.5281/zenodo.1050060 2d28bebf-e3c5-457b-9152-8a6877ded281 1175-5326 1050060 Key to Groups of New World Hydraena 1 Posterior ridge of genae present, at least laterally (e.g., Figs. 2 c, 2d); abdominal intercoxal ventrite various; scintilla absent ... 2 1' Posterior ridge of genae absent (e.g., Figs. 44 , 126 ) or nearly imperceptible; abdominal intercoxal ventrite flat, with posterior margin straight or weakly arcuate; scintilla ( Fig. 2 b) present or absent........................................... 5 2 Elytra and labrum with spines ( Figs. 21 , 22 ); elytron with five rows of punctures between suture and humerous; two species from South America ...................................................................... Multispina Group 2' Elytra and labrum without spines; elytron with more than five rows, or with many random punctures................... 3 3 Abdominal intercoxal ventrite concave, with posterior margin markedly arcuate; elytral punctures serial or, in few adults, with few random punctures on disc; spermatheca C-shaped; female gonocoxite not divided; Canada and the United States ............................................................................................... Circulata Group 3' Abdominal intercoxal ventrite flat, with posterior margin straight or weakly arcuate; elytral punctures random, at least near base; spermatheca disc-shaped (e.g. Figs. 151–154 ) or (in H. paeminosa ) trilobed ( Fig. 155 ); female gonocoxite divided ( Figs. 148–150 ); South America .............................................................................. 4 4. Elytral punctures coarse and very random (e.g., Fig. 3 ); pronotum more elongate; mesoventral intercoxal process (P2) very narrow, tapering to sharp point that is contiguous with midlongitudinal carina of metaventrite (e.g., Fig. 2 c).................................................................................................... Paeminosa Group 4'. Elytral punctures serial except in small area at base ( Figs. 16–18 ); pronotum less elongate, sides more sinuate; mesoventral intercoxal process (P2) wide, apex blunt (e.g., Fig. 2 d)............................................ Curvosa Group 5 Pronotal scintilla ( Fig. 2 b) present or absent; pronotum always with posteromedial foveae (PF2; Fig. 2 a)...... Leechi Group 5' Pronotum never with scintilla; pronotum without posteromedial foveae, or if present very shallow and pronotum coarsely punctate (e.g., Figs. 110 , 118 )........................................................... Marginicollis Group